Family: Ostreidae, Oysters view all from this family

Description 1 1/2-5 1/2" (3.8-14 cm) long. Large, broadly ovate to almost circular, thick-shelled, usually attached by right valve. Exterior whitish, yellow, or orange to reddish-brown; early part of left valve often lighter or reddish and spotted; ribs and riblets on left valve with erect spines; right valve may have dense, leafy concentric ridges. Interior smooth, whitish, light brown or reddish on ears, with finely grooved margin often purple, brownish, orange, or yellowish.

Habitat On rocks, coral reefs, submerged wrecks, and sea walls, in water 1-150' (0.3-46 m) deep.

Range North Carolina to Brazil.

Discussion In deep, quite waters the spines grow very long and delicate. The closely interlocking hinge teeth work so effectively that it is often difficult to separate the valves without damaging the teeth.